1. Field of the Invention
This invention relates to the field of medical diagnostic devices.
2. Discussion of the Related Art
The prevalence of diabetes is increasing markedly in the world. At this time, diagnosed diabetics represent about 3% of the population of the United States. It is believed that the actual number of diabetics in the United States is much higher. Diabetes can lead to numerous complications, such as, for example, retinopathy, nephropathy, and neuropathy.
The most important factor for reducing diabetes-associated complications is the maintenance of an appropriate level of glucose in the blood stream. The maintenance of the appropriate level of glucose in the blood stream may prevent and even reverse some of the effects of diabetes.
Glucose monitoring devices known in the art have operated on the principle of taking blood from an individual by a variety of methods, such as by means of a needle or a lancet. The individual then contacts a strip carrying reagents with the blood, and finally inserts the strip into a blood glucose meter for measurement of glucose concentration by optical or electrochemical techniques.
Medical devices of the prior art for monitoring the level of glucose in the blood stream have required that an individual have separately available a needle or a lancet for extracting blood from the individual, test strips carrying reagents for bringing about a chemical reaction with the glucose in the blood stream and generating an optical or electrochemical signal, and a blood glucose meter for reading the results of the reaction, thereby indicating the level of glucose in the blood stream. The level of glucose, when measured by a glucose meter, is read from the strip by an optical or electrochemical meter.
It is desired to simplify the systems, devices, and methods for determining the level of an analyte such as glucose in a body fluid such as blood. In particular, it is desired to integrate the operations of extracting a sample of blood by means of a needle or a lancet, applying the sample of blood to a reagent-bearing test strip, reading the result of a glucose monitoring test, and discarding the used needle or lancet and test strip in a safe and efficient manner.
Certain patents describe devices that can perform steps for determining the concentration of glucose in the blood stream. For example, U.S. Pat. No. 5,632,410 discloses a sensor-dispensing instrument for handling a plurality of fluid sensors (i.e., test strips). However, this patent fails to include a lancing device for puncturing the skin of a patient in order to extract a sample of blood. U.S. Pat. No. 6,908,008 discloses an apparatus that includes a dispenser comprising a housing having a chamber; a means for retaining a plurality of test strips in a substantially moisture-proof, air-tight first position; and a means for opening the chamber and moving one of the plurality of test strips translationally from a first position inside of the chamber to a second position at least partially outside of the chamber, wherein the opening of the chamber and the moving of the one test strip is achieved by a single mechanical motion; and an electrochemical analyzing means for analyzing a biological fluid. However, like, U.S. Pat. No. 5,632,410, this patent fails to simplify the testing process, e.g., this patent fails to include a lancing device for puncturing the skin of a patient in order to extract a sample of blood.
U.S. Pat. No. 5,035,704 discloses a blood sampling mechanism including a test pad of a predetermined thickness set-off between opposite relatively closely spaced surfaces imparting a thin configuration to said test pad, said test pad carrying a dermis-piercing member having a pointed end, said pointed end being disposed inboard of said opposite surfaces, means for applying a force to said dermis-piercing member in a direction to move said pointed end beyond one of said opposite surfaces to pierce the dermis and thereby obtain a blood sample, means for testing the blood sample, means for defining a blood sampling station at which the blood sample is obtained, means for defining a blood testing station at which the blood sample is tested by said blood sample testing means, and means for conveying said test pad from said blood sampling station after the blood sample has been obtained to said blood testing station. The dermis-piercing member and test pad are, however, entirely separate components in this system (see also WO 03/082091). U.S. Pat. No. 5,971,941 discloses a blood sampling apparatus for sampling blood from the skin of a patient for analysis. The apparatus includes a cartridge and a housing with a driver. The cartridge has a cartridge case, lancet, and a compartment associated with the cartridge case for receiving blood. The lancet is housed in the cartridge case and operatively connected thereto such that it is drivable to extend outside the cartridge case through a lancing opening for lancing the skin to yield blood. The housing has a driver for urging the lancet to extend outside the cartridge case. During lancing, the cartridge may be detachably held in the housing such that the cartridge can be disassociated from the driver after sampling blood. The U.S. Pat. No. 5,971,941 discloses that material around a lancet aperture in a cartridge case soaks up blood after lancing (see also U.S. Pat. No. 5,279,294). This does not bring the absorbent material to the center of the sample, and when only a small amount of blood is available such as is often the case in alternate site testing away from fingertips, then testing may be unreliable, may need to be repeated far too often, or may simply require testing at the fingertips. Application of sample fluid to a capillary end leading to reagent material involves careful manual alignment. A manual actuation step is also involves in getting the lancet to protrude from the cartridge.
WO 2004/041082 discloses a device for use with a body fluid sampling device for extracting bodily fluid from an anatomical feature. The device comprises a cartridge having a plurality of cavities. The device may include a plurality of penetrating members each at least partially contained in the cavities of the cartridge wherein the penetrating members are slidably moved to extend outward from openings on the cartridge to penetrate tissue. The device may also include a plurality of analyte detecting members and a plurality of chambers. Each chamber may be associated with one of the cavities, the chambers positioned along an outer periphery of the cartridge, wherein at least one of the analyte detecting members forms a portion of one wall of one of the plurality of chambers.
U.S. Pat. No. 6,352,514 discloses a body fluid sampling device that includes a lancet and a test strip. The lancet is disposed on a lancet carrier, while the test strip is disposed at the end of a capillary tube. Body fluid exposed at a lancing site is drawn up into a capillary tube which is placed into contact with the body fluid. At the end of the capillary tube is a test strip. Once the body fluid is drawn up the capillary tube, it may be applied to the test strip to determine an analyte level. The lancet and the capillary tube and test strip are contained within a same sampling device housing, although they are configured as two separately disposable items and not integrated together as a single item. These items are separately manipulated into, within and out of the housing before, during and after use, respectively.
It would be desirable to develop a test sensor that also serves as a lancet for forming an opening in the skin of a patient to enable a sample of biological liquid to emerge from the patient, so that the sample of bodily fluid may be collected from the patient emerging from the opening in the skin by a test strip, and analyzed to determine a characteristic of the bodily fluid. It would also be desirable to develop a medical diagnostic device that is small in size, reliable to use, and provides accurate results, even when only a small volume of sample of biological liquid is collected.